Throughout recorded history man has used horological instruments for indicating time. These devices have evolved from the most crude forms of sundials to the ultra-precise chronometers used today in navigation and astronomy. The sundial type horological instruments have one pronounced attribute ancillary to its time indicating capability, namely its ability to portray a relation between the passage of time and the relative movement of our planet earth with respect to the sun. This facet is of continuing importance to adults since the passage of time is psychologically so closely associated with the various periods of the day. For children, the sundial offers a unique educational instrument useful in the learning of both time recognition as well as in its association with the movement of heavenly bodies and the various periods of the day.
Notwithstanding the just-mentioned attributes of sundial type horological instruments, they exhibit several obvious disadvantages. Firstly, the use of sundials is limited to those daylight hours when the sun is locally positioned to cast a shadow on the instrument and even then only to those portions of such periods in which the local weather conditions permit the sun to cast a discernible shadow on the dial. In addition, sundials must be located out-of-doors or in such specialty types of enclosures which permit the rays of the sun to strike the dial during most of the day. Furthermore, popular sundials are quite inaccurate due to their seasonal variations, their longitudinal and latitudinal placement within governmentally established time zones, and legislatively enacted changes in local time such as between standard and daylight saving time.
Most modern day timepieces, of course, are not of sundial construction at all but rather employ two or more hands coupled with motor means for continuous movement over a dial. These timepieces have a relatively high degree of accuracy as well as other attributes such as compactness, readibility, portability and longevity. Notwithstanding these attributes most timepieces in modern use exhibit no relation to the various periods of daylight hours or any association with planetary movement. This leads to a dehumanizing effect upon adults and to difficulty in training children in time recognition and its relation with the heavens. Should a horological instrument be devised that possessed the attributes of both sundials and timepieces, a very decided advance in the art would be achieved.
Accordingly, it is the general object of the present invention to provide an improved horological instrument.
More specifically, it is an object of the invention to provide a horological instrument which is capable of indicating time with both accuracy and a symbolic association with relative movement of our planet with respect to the sun.
Another object of the invention is to provide a horological instrument which may be readily used in educating children in the principles of time recognition and its heavenly body basis.
Yet another object of the invention is to provide a horological instrument of the type described which is attractive in appearance and duable and requires little or no periodic adjustment.
In one form of the invention a horological instrument is provided comprising a dial, an electrically energizable light source, gnomon means for casting a shadow on the dial, and means for imparting relative movement between the electrically energizable light source and the dial to move the shadow on the dial in indicating time.
In another form of the invention a horological instrument is provided comprising a dial, a gnomon mounted above the dial, means for directing a beam of light along a beam path onto the gnomon and dial, and means for moving the beam path about the gnonom to cast a shadow on the dial indicative of time.